Alternating-current motor



March 9,1926.

INVENTOR Patented Mar. 9,.192 6.

UNITED STATES PATENT OFFICE.

HANS WEICHSEL, OF ST. LOUIS, MISSOURI, ASSIGNOR TO WAGNER ELECTRIC COR-PORATION, OF ST. LOUIS, MISSOURI, A CORPORATION OF DELAWARE.

ALTERNATING-CURRENT MOTOR.

Application filed May 15,

To all 'whom z't may concern Be it known that I, HANS VVnIoIIsnL, acitizen of the United States of America, residing at the city of St.Louis, State of Missouri, United States of America, have invcnted acertain new and useful Alternating-Current Motor, of which the followingis such a full, clear, and exact description as will enable any oneskilled in the art to which it appertains to make and use the same,reference being had to the accompanying drawings, forming part of thisspecification. 1

My invention relates to an alternating current dynamo electric machineand par ticularly to multipolar synchronous and asynchronous alternatingcurrent motors which have a commuted winding for producing an excitingE. M. F. The invention comprises connections and relations of wind-'ings and brushes which avoid the use of cross-connectors between brushesof like po-. larity andprevent cross-currents that would develop inmachines of this type it such cross-connector were used and wouldadversely afiect commutation and increase internal losses. Otherfeatures and advantages of my invention will be hereinafter more fullydescribed.

My invention is applicable to single phase as well as polyph-ase motorsand to those having any number of poles more than two. In theaccompanying drawing I have illustrated a four-pole polyphasesynchronous motor embodying my invention.

The rotor and stator are lireferably constructed without defined p0 arprojections and with small air-gap, as is usual in induction motors. Inthe machine shown the rotor is the. primary member and is provided witha polyphase winding supplied with current through slip rings 1,2 and 3and with a fourpole' commuted winding 4. The stator is provided withexciting windings 5 and G adapted to produce four-pole magnetizatiomjandon the commutator are located two pairs of brushes'Z-S and 9-10. Asshown, these brushes are displaced by a small angle from the axes of thewindings for the purpose of producing a good syn chronizing torque and aunidirectional excitation in synchronous operation, one com- -'ponent ofwhich is so located as to satisfactorily influence the power factor, as

sides of the armature.

1924. Serial No. 713,422.

scribed in my .previous application, No. 674,131.

In accordance with my inventionl connect each exciting winding-in serieswith brushes of like polarity, winding 5 being Serial in series withpositive brushes 7-8 and winding 6 in series with the negative brushes9.10. With this arrangement any cross-currents between brushes of likepolarit '-wliich may result from inexact spacing of the brushes, slighteccentricity ot' the rotor with respect to the stator, and variation ofmagnetic density from other causespass through the exciting windings.Due to the resistance of these windings the magnitude of these currentsand therefore the losses and disturbing effects thereof are very greatlyminin'iized. The circuit. between the positive and negative brushes iscompleted ings 5 and 6, this connection being through adjustableresistance 11. It will be understood that the drawing is not intended toshow the actual space positions of the parts of windings 5 and 6 onopposite sides of the points of connection to resistance 11. The twoparts of these windings magnetize in opposite directions and are onopposite provided with starting windings 12 and 13 connected in seriesthrough adjustable re sistance 14 and having their axes displaced,preferably by ninety electrical degrees, from the axes of the excitingwindings.

Referring to the operation of the motor described, at starting theresistances 11 and 14 are adjusted to suitable value and the slip ringsare connected to the supply. The windings 5-6 and 12-13 act as polyphasesecondary windings and the machine starts with good torque andrelatively small current. As the speed increases the resistances 11and14 can be reduced in one or more steps until the windings 12 and 13areshort-circuited and the resistance 11 brought to its operating-value.It will be understood that at synchronism unidirectional current will besupplied to the exciting windings from the commutator and aunidirectional exciting magnetization thereby produced.

It will be noted that the arrangement described permits the use of asingle resistance 11 in the exciting circuit instead of two separateresistances whichwould be necessary by connecting the middle points ofthe wind- The stator is also. I

if each exciting winding were in circuit with positive and a negativebrush and not 111- a plurality of-brushes on the commutator,' one ofsaid exciting windings be1n 'nnected in series with a pair of brus es'ofpositive polarity and a second exciting windmg being connected in serieswith a pair of brushes of negative polarity, and means fof':

interconnecting said exciting windings.

2. In an alternating current motor, the combination of an inducingmember provided with a commuted winding, an induced member provided witha plurality of exciting windings adapted to produce an N-polemagnetization of more than two poles, a plurality of brushes on thecommutator, one of said exciting windings being connected in series witha pair of brushes of positive polarity and a second exciting windingbeing connected in series with a pair of brushes of negative polarity,and means for inter connecting the middle points of said ing windlngs.

3. In an; alternating current motor, the

excit-- combination of an inducing member-pro vided with a commutedwinding, an induced member provided with a plurality of excitingwindings adapted to produce N-polemagnetization of more than two poles,a plurality of brushes on the commutator, one

of said exciting windin being connected in series with a pair of rushesof (positive.

polarity anda second exciting win ng being connected in-series with apair of brushes of negative polarity, and means comprising an adjustableresistance for interconnect- -ing said exciting windings.

4.7111 an alternating current motor, the

combination of an inducing member pro;

vided with an inducing winding and a com muted winding, an inducedmember rovided with a, plurality of exciting windings adapted to producean N-pole'magnetization of more than two poles, a plurality of brusheson the commutator, one of said exciting windings being connected inseries with a pair of brushes of; positive polarity and a secondexciting winding bem connected in series with a pair of brushes ofnegative polarity, means for interconnecting said exclting windings, and!a secondary winding on the induced member axially 'displaced from theexciting windings.

5. In an alternating current'motor, the combination of an inducingmember provided with a commuted winding, an induced member provided witha plurality of exciting windings'adapted to produce an N-pole manetization of more than two poles, a plura 'it' of brushes on the,commutator by means 0 which exciting E. M. F. is supplied to theexciting windings, the brushes and excitin windings beingso connectedthat the on y current path external to the commuted winding betweenbrushes of like polarity is through an exciting winding.

In testlmony whereof, I have hereunto set my hand this the 12th day ofMay, 1924.

iiANs WEICHSEL.

t i xii-Ml

